The present invention relates to a method of making a unitary construction element having a dual thermal barrier or thermobreak therein, commonly referred to as a thermal barrier extrusion, which can be employed in construction of windows, doors, frames therefor, and the like.
The invention generally relates to a method of making or forming dual thermal barrier hollows, especially dual thermal barrier hollows wherein the thermal barrier material is poured into a receiving channel or area in an extrusion.
The invention particularly relates to a method of forming a dual thermal barrier hollow or unitary construction element wherein two separate aluminum solid extrusions are joined together by a poured polyurethane resin or the like to form a single dual thermal barrier hollow.
With the advent of metal construction used in making windows, doors, frames therefor, curtain walls and the like, problems of heat conduction and water condensation have arisen. The use of aluminum or other metals has caused a greater transfer of heat between wall elements than had heretofore taken place in earlier types of construction. To solve this problem, some type of insulating or thermal break construction is essential. Accordingly, a variety of thermal barrier or thermobreak constructions and methods and apparatuses for making such constructions have been developed.
One type of construction which has achieved some degree of success is one in which the insulating material is poured, flowed, foamed, or formed in place. U.S. Pat. Nos. 3,204,324; 3,332,170; 3,393,487; 3,624,885 (Re. 28,084 and Re. 28,086); 3,634,565; and 3,823,524 are illustrative of such types of construction. Of these, 3,204,324 is representative of a method of making a thermal barrier construction element or insulating construction, wherein a metal shape having a generally U-shaped channel therein is filled with a flowing resinous insulating composition; the composition is cured, and subsequently a portion of the metal member or web forming the base of the channel is removed. U.S. Pat. No. 3,823,524 relates to a similar method but employs a web member which extends convexly between the structural member forming the channel. Both of these methods require the use of a liquid resinous composition which is subsequently cured or hardened. U.S. Pat. No. 3,393,487 discloses a somewhat more complicated process for making a thermal insulating joing construction and also utilizes a liquid plastic material. In such process, two separate elongated metal shapes are spaced apart and fastened together with a solid first insulating member. The two shapes and the first insulating member provide a channel in which a second thermal insulating member is flowed therein. Upon solidification of the latter, the metal and insulating members are locked together as an integral unit.
Of the more common types of thermal barrier constructions, two metal members are joined together by a solid insulating member. These constructions encompass a wide variety of insulating and/or plastic shapes and metal shapes. Illustrative of these are U.S. Pat. Nos. 2,835,360; 3,093,217; 3,099,337; 3,289,377; 3,436,884; 3,487,580; 3,600,857; and 3,916,503. In one of the more basic of this type of construction, for example, in U.S. Pat. No. 2,835,360, two metal members are joined together and spaced apart by an overlapping insulating member. In 3,916,503, simple mechanical means are employed to join the metal members with an insulating member. U.S. Pat. No. 3,600,857 is representative of more complex shapes of insulating and metal members.
In a particular type of the foregoing more common type of thermal barrier constructions, metal and insulating members are mechanically joined together by deformation of the metal members or by crimping or stitching the metal members on the insulating member. Representative of such a joining method are U.S. Pat. Nos. 3,114,179; 3,411,995; 3,420,026; 3,517,472; and 3,903,217 and Swiss patent No. 320,988 (same as British patent No. 768,499). For example, U.S. Pat. No. 3,420,026 discloses several types of thermal insulating members and methods of making them. In one type, two separate metal members are mechanically joined to a central insulating member by crimping or deformation of groove means or projections on the metal members. In one particular type of thermal break construction, the insulating member is in the shape of a Maltese cross in cross-section. In another embodiment, the insulating member is made from a thermoplastic material and a portion thereof is heated to cause melting and flow of the plastic into an associated groove means formed by the two metal members. Upon cooling of the plastic, the metal and plastic members are unitarily joined together. U.S. Pat. No. 3,517,472 also illustrates a mechanical joining process similar to that of the former and additionally represents the use of a plastic or insulating member which expands upon heating. The Swiss patent discloses several types of window or door frames, one of which employs a crimp system using two separate metal extrusions having a pair of flanges thereon which form grooves for receiving a plastic rod. After the plastic rod or thermal barrier member is introduced into the grooves, the flanges are pressed towards the plastic rod or crimped thereon so that they are flush with the sides of the rod.
Other types of thermal break or insulated window or wall constructions are illustrated by U.S. Pat. Nos. 2,654,920; 3,055,468; 3,289,377; 3,411,254; and 3,446,801. For example, U.S. Pat. No. 3,411,254 provides a plastic thermobreak which utilizes a plastic locking strip which contains a heat actuated blowing agent to join two separate metal shapes. After assembly of the two metal shapes and the plastic strip, the unit is heated to expand the plastic into tight engagement with the two metal members.
More recent types of thermal barrier construction methods are illustrated by U.S. Pat. Nos. 3,815,216; 3,916,503; 3,925,953; 3,992,769; 4,079,496; 4,151,682; and 4,188,705.
U.S. Pat. No. 3,815,216 employs a metal extrusion which has a removable interior section which is subsequently removed to separate the extrusion into two metal members. While maintaining the separate metal members spaced apart, a plastic material is inserted therebetween. The construction element can be made in a continuous operation.
In U.S. Pat. No. 3,916,503, lineal shapes are extruded to accept an insulating barrier previously formed in such a shape as to fit the lineal shapes. The insulating barrier is joined with the lineal shapes by mechanical means.
U.S. Pat. No. 3,925,953 discloses a method wherein two metal members are joined together by a plastic clamp and held apart by a plastic wedge.
U.S. Pat. No. 3,992,769 describes a method wherein a metal shape is extruded in a normal manner and the insulating member is crimped in position in the metal extrusion and a portion of the metal extrusion is subsequently removed.
U.S. Pat. No. 4,079,496 discloses a method wherein a pair of lineal metal shapes are aligned in a spaced apart relation and the insulating member has small lineal projection thereon which are shaved off to provide a tight or interference fit, when the insulating member is inserted between the metal shapes so as to join them together.
U.S. Pat. No. 4,151,682 discloses a thermal barrier window construction wherein centered rigid extended plastic shapes are included in the window frame.
U.S. Pat. No. 4,188,705 illustrates a crimping or stitching apparatus. In such a crimping system, rollers are normally used to provide crimping of the metal flanges on the insulating or plastic member. Conventionally, two rollers or wheels are required to crimp the flanges. One roller bends the metal flanges on the insulating member while the other roller backs up or holds the metal extrusion in the correct position for joining metal and plastic members. To accomplish the crimping action, clear access must be available on both sides of the plastic members on which crimping of the metal members occurs. In some cases, a small wheel or support is laterally employed to serve as a back-up. The size of the support and the forces required to obtain a tight joint create a number of operating problems. The types of shapes or extrusions which can be used in this method are limited.
Large window shapes such as mullions, rails and sills used in thermally insulated windows often require two separate thermal barriers to maintain structural integrity. The present invention provides hollow shapes which cannot be readily debridged or separated because of their geometry.
The present invention provides a number of advantages over prior art constructions namely in that solid extruded shapes can be quickly and easily joined together to form a poured urethane dual thermal barrier construction element having structural integrity.
It is a primary object of the instant invention to provide a relatively simple method of making a dual thermal barrier hollow utilizing solid lineal shapes or extrusions.
Other objects and advantages of the present invention will become more readily apparent from a consideration of the description and drawings hereinafter.